Proceedings and Collections. 35 



the jtnra. It La Arcenlhobium puuUlum^ a little plant allied 

 to the true Mistletoe, and hitherto aol discovered oottide of 

 the State of New York, it is parasitic on the branch" 



the Black Spruce Of the mountain swampy. It la a OUriouS 



fact that it was not even known to science until 1871, when 

 it was discovered l>y Miss L. A. Milling n>.\ in Warren 

 County, New York. Since then stations have been discov- 

 ered in Essex, Benssalaer, Saratoga, Herkimer, Oswego, and 

 Sullivan Counties of New York, last year by myself in 

 Seneca County, New York, and Lackawanna and Monroe 

 Counties in Pennsylvania. It may be looked for farther south, 

 as the Biack Spruce extends into North Carolina, and there 

 is no reason to suppose it affects the North like so many of 

 the plants about it. Nevertheless this plateau, in its un- 

 disturbed tracts, is remarkable for the predominance of north- 

 ern plants, some of which find here their southern limits, 

 some extend along the Alleghenies in a narrowing belt to 

 their southern termination in North Carolina. In striking 

 contrast to what has been mentioned above are the low, nar- 

 row valleys, 500 to 700 feet above tide, such as the lower part 

 of the Lackawanna and the more alluvial Wyoming. The 

 richer soil, the sheltered areas and the shores of a river afford 

 an entirely different series of plants. The Cottonwood, the 

 Silver Maple, the American Elm are frequent here, with oc- 

 casional Black Walnuts. Here also, along the river banks, 

 is a characteristic and picturesque tree, with a rich, salmon- 

 colored bark— the River Birch {Betula nigra). It forms groves 

 along the Susquehanna, and Everhart's Island, on the lower 

 Lackawanna, is nearly covered with a fine growth of them. 

 They have been noticed above Scranton to Peckville, but prob- 

 ably disappear with the changed character of the valley above 

 Archbald. The Wild Yam is occasional in the Lackawanna 

 and Wyoming Valleys, and where the Susquehanna breaks 

 across at Mocanaqua, occurs Dlanthcra, a plant of the larger 

 river and lake shores, conspicuous on the lower Susquehanna 

 and the lower Juniata, but not known on the Delaware or its 

 branches, or hitherto on the upper Susquehanna. Here also 

 is Physostegia Virginiana, a handsome flowered western plant, 



